Stator compound having an NBIR terpolymer elastomeric base and stators and downhole motors using the same

Abstract

A stator compound including an acrylonitrile butadiene isoprene rubber (NBIR) terpolymer elastomeric base.

What is claimed is: 
     
       1. A method of making a stator compound, comprising:
 during a first mixing stage, mixing a high reinforcing carbon black with an acrylonitrile butadiene isoprene rubber (NBIR) terpolymer elastomeric base, which has not been hydrogenated, at a temperature below about 300 degrees Fahrenheit without curing agents to produce a mixture; 
 allowing the mixture to cool to ambient temperature; and 
 during a second mixing stage, mixing curing agents into the mixture. 
 
     
     
       2. The method of  claim 1 , wherein mixing a high reinforcing carbon black with the NBIR terpolymer elastomeric comprises mixing a high reinforcing carbon black having a surface area of about 80 to about 250 (Iodine # mg/g) and a structure of about 70 to about 178 (DOP Absorption- cc/100 g). 
     
     
       3. The method of  claim 2 , further comprising mixing a semi-reinforcing carbon black with the NBIR terpolymer elastomeric base during the first mixing stage. 
     
     
       4. The method of  claim 3 , wherein mixing a semi-reinforcing carbon black with the NBIR terpolymer elastomeric base comprises mixing a semi-reinforcing carbon black having a surface area of about 20 to about 50 (Iodine # mg/g) and a structure of about 60 to about 125 (DOP Absorption- cc/100 g) with the NBIR terpolymer rubber. 
     
     
       5. The method of  claim 1 , further comprising mixing at least one plasticizer selected from the group consisting of polymeric and ester plasticizers with the NBIR terpolymer elastomeric base during the first mixing stage. 
     
     
       6. The method of  claim 1 , wherein mixing curing agents into the mixture comprises mixing sulfur into the mixture during the second mixing stage. 
     
     
       7. The method of  claim 1 , further comprising mixing an antioxidant with the NBIR terpolymer elastomeric base during the first mixing stage. 
     
     
       8. The method of  claim 1 , further comprising mixing at least one of a phenolic resin without a curing agent, zinc oxide, stearic acid, and hexamethylene tetraamine with the NBIR terpolymer elastomeric base during the first mixing stage.